1. Technical Field
The present invention generally relates to physical values of mechanical parts and, more particularly, to an apparatus and method for simultaneously calibrating a moment-of-inertia and a center-of-gravity.
2. Related Art
Generally, since a machine moves dynamically, a center-of-gravity and a moment-of-inertia of each of parts constituting the machine should be individually calibrated. Assuming that there is a rotor whose center-of-gravity and moment-of-inertia are wrongly calibrated, inertia force generated when the rotor slightly loses its balance creates a force several times larger than the weight of the rotor, thereby degrading the entire performance of the machine. Therefore, it is very important to accurately and easily calibrate a center-of-gravity and a moment-of-inertia of specific parts constituting the machine.
In the prior art, there exist methods and apparatuses which calibrate a center-of-gravity or a moment-of-inertia of specific parts constituting a machine which moves dynamically. For example, such methods and/or apparatuses are disclosed in the following patents: U.S. Pat. No. 4,319,188 to Ito et al., entitled Magnetic Rotary Encoder For Detection Of Incremental Angular Displacement, U.S. Pat. No. 4,350,852 to Neyret, entitled Bi-Stable Mechanism And Anti-Theft Device For A Motor Vehicle Comprising Such Mechanism, U.S. Pat. No. 4,890,059 to Guentner, entitled Digital Tachometer With Air Gap Adjusting Yoke Insertable Through Holes In The Tachometer Housing, U.S. Pat. No. 5,081,865 to Schechter et al., entitled Center Of Gravity Locating Method, U.S. Pat. No. 5,177,998 to Monk, entitled Center Of Gravity And Moments Of Inertia Measurement Device, U.S. Pat. No. 5,293,125 to Griffen et al., entitled Self-Aligning Tachometer With Interchangeable Elements For Different Resolution Outputs, U.S. Pat. No. 5,349,438 to Solomon, entitled Structure For The Dynamic Support Of A Reflective Element And Interferometer Comprising the Same, U.S. Pat. No. 5,367,909 to Heilman et al., entitled Test Weight, U.S. Pat. No. 5,537,272 to Kazmierczak et al., entitled Spindle Balance Device For A Hard Disk Drive Assembly, U.S. Pat. No. 5,559,728 to Kowalski et al., entitled Calibration Transfer For Second Order Analytical Instruments, and U.S. Pat. No. 5,656,768 to Abler et al., entitled Method For Determining The Moment Of Inertia.
The problem with such methods and apparatuses of the prior art resides in the fact that such methods and apparatuses typically calibrate only the moment-of-inertia or the center-of-gravity. Furthermore, typical methods and/or apparatuses for calibrating the center-of-gravity calibrate that quantity only for an object having a gimbal structure.
Referring to the above-identified patents, by way of example, Abler et al. '768 discloses method for determining the moment-of-inertia only, and such method is directed to determination of the moment-of-inertia for an internal combustion engine in particular. Moreover, Monk '998 discloses a device for calculating the center-of-gravity and moment-of-inertia, but such device is directed to calculation of those quantities for vehicle only. Finally, Schechter et al. 865 discloses a method and system for determining the center-of-gravity of a body, but such system and method do not provide for the determination of a moment-of-inertia.
Therefore, there is a need in the prior art for the development of a method and apparatus for simultaneously calibrating both the moment-of-inertia and the center-of-gravity. Moreover, there is a need for the development of a method and apparatus for easily calibrating a moment-of-inertia and a center-of-gravity for an object having a complicated shape, as opposed to an object having a defined structure (such as a gimbal structure). Finally, there is a need for the development of a method and apparatus for easily calibrating a moment-of-inertia and a center-of-gravity for a as movable part mounted in a multi-axis rotation system.